Device for measuring forces and torque in different directions

Abstract

A device for measuring forces and torque in different directions. The device includes a rigid, round hub and an annular flange that is disposed parallel to the hub. The flange and the hub are connected to one another via four spokes that are arranged in the shape of a cross. The spokes are deformed by a load due to their dimensions. Such a deformation is measured with the aid of elongation-measuring strips, with the hub and flange remaining rigid. The inner ends of the spokes are secured in the hub, while the outer ends are secured to the flange via thin members, the thickness and diameter of which are such that the members yield readily in response to transverse forces and torsion of the spokes about their axes, while tangential displacements are substantially eliminated. The diameter of each member is at least 2.5 times as great as the diameter of the spokes, and the thickness of a given member has an upper limit. Such a device assures a high sensitivity to measurements, and a separation of the load components.

What I claim is: 
     
       1. In a device for measuring forces and torque in different directions, said device including a rigid, round hub and an annular flange that is disposed parallel to said hub, with said flange and said hub being connected with one another via four spokes that are arranged in the shape of a cross, are secured in said hub, and are deformed by a load due to their dimensions, with such a deformation being measured with the aid of elongation-measuring strips, with said hub and said flange themselves remaining rigid, the improvement wherein: each of said spokes has an outer end remote from said hub, with each outer end being secured to said flange via a respective thin, circular member, the thickness and diameter of which are such that each member yields readily in response to deflection and pivoting of said spokes about tangential axes, while tangential displacements are substantially eliminated; the diameter of each of said circular members is at least 2.5 times as great as the diameter of said spokes, and the thickness of each such member has an upper limit defined by the equation ##EQU24## where f member  is the maximum deflection of the member, f B  is the maximum deflection of the spoke, k 1  is a function of β,β equals 2R/a, R is the radius of the member, a is the thickness of the spoke, h is the thickness of the member, and l is the length of the spoke. 
     
     
       2. A device according to claim 1, in which said elongation-measuring strips are utilized in a dual role and comprise half bridges, the potentials of which are fed both to a first group of measurement amplifiers that measure force, as well as to a second group of measurement amplifiers that measure torque. 
     
     
       3. A device according to claim 2, in which said hub and said flange are provided with bores, with safety bolts being fixedly disposed in the bores of said hub, and the same safety bolts being disposed with play in the bores of said flange to allow for deformation within the measuring range. 
     
     
       4. A device according to claim 3, in which each of said spokes has a solid profile with a square cross-sectional shape. 
     
     
       5. A device according to claim 3, in which each of said spokes has a solid profile with a round cross-sectional shape. 
     
     
       6. A device according to claim 3, in which each of said spokes has a hollow profile in the shape of a square box. 
     
     
       7. A device according to claim 3, in which each of said spokes has a hollow profile in the shape of a tube.